(Note:
this is the revised chapter from the original Fruits and Berries book that
due to space considerations was unable to be included in the Fruit
Gardener's Bible.)

A friend visiting us from Mexico commented, “You spend lots of
time talking about the weather. We hardly ever mention it at home.” Our
daughter asks why adults are always talking about the weather. We realized
they were right. The weather plays an important part in our lives because
it constantly affects our plans, as it does those of most gardeners. About
forty years ago, I began to keep a daily record of weather and
temperature, hoping that the information would help us better plan our
growing program. Two decades later, all I really knew for sure was that
New England weather is cussedly unpredictable, which any Yankee could have
told me in the first place.Now
I can blame the extremes in our weather either on El Niño if it is
happening that year, or on global warming. We have a saying in Vermont,
which I imagine many other states have as well, that if you don't like the
weather, wait a minute until it changes.

Our weather may change several times a day, or get bogged down and
stay the same every day for six weeks. The last frost of spring hits our
crops in northeastern Vermont any time from late April to late June, and
the first fall frost may come as easily as late august or as late as early
November. We often joke about what day summer occurred this year.Snow might arrive first in mid-September or in mid-December, and
snowstorms of a foot or more have descended upon us in late May.

Nearly every part of North America has similar surprises on the
weather scene. Each year we hear of crop failures in one area or another
due to unusual weather conditions from droughts to floods. Whether in New
Jersey, Idaho, Minnesota, or even the Deep South, sudden temperature
changes occasionally ruin the fruit crop. Few areas can be absolutely
certain of a good harvest every year.Burrrrrrrr,
It's Cold!

Of the weather variables that can affect fruit crops, other than
water, a main one is temperature.In
warm climates this can relate to the need for chilling, already described,
but in many areas the concern is winter cold.There are many ways in which cold weather can affect trees, and
even the experts are baffled by some forms of winter injury. Extremely low
temperatures can cause damage, but, surprisingly, it isn’t always the
frigid temperatures that do the most harm. Injury is sometimes most severe
during mild winters, because sudden fluctuations can cause as much damage
to trees as low temperatures. A long January thaw may induce the tree to
start growing, or a warm sun in March may quickly heat its brown bark. In
both cases the return to below-freezing is a severe shock and can even be
fatal to the tree.

It also depends on when the cold weather occurs.Hardy plants, both herbaceous perennials and woody trees and
shrubs, develop their resistance to cold gradually during the fall.While they may not take even mild sub-freezing temperatures in
October, they can tolerate much colder in January when fully hardened.A similar but reverse process happens in spring, which is why
early-blooming trees are often damaged by spring frosts.

Any long duration of cold can hurt a tree, too, as can extended
periods of wind chill. Like animals and humans, a hardy tree can stand
considerable cold for a short period, but it will suffer if the situation
continues for days. So even if a temperature isn't extremely cold, if it
lasts long enough it can cause similar damage.

You may not discover winter damage until spring, when whole limbs
may fail to leaf out. Or you may notice large cracks where the bark of the
trunk has split open, loosened, and started to come off. These open wounds
create ideal conditions for fire blight, cankers, rots, and other
infections. Inspect your trees in later winter and promptly deal with any
injury.Choose a warm
day when the wood isn’t frozen, and cut off all limbs damaged by ice or
snow.

Weather also often causes stress and subsequent damage to trees and
plants that may not show up until later in the growing season. One spring,
following a dry summer and hard winter, many of our young trees leafed out
beautifully, only to wither and die within a few weeks. The long period of
stress had weakened them enough so they didn’t have the stamina to
continue to grow.

What Trees Are Hardy in Your Area?

When buying new trees, select kinds that are acclimated and can
stand the weather expected for your region. If you have extra room, it is
always fun to experiment with a few that are intended for a warmer zone
(see next section on Microclimates), but for most of your planting
you’ll want to stack the odds in your favor.There is a great difference in hardiness sometimes among cultivars,
so pay attention to the hardiness for each.Just because a particular fruit type is listed for a certain
hardiness range, doesn't mean all cultivars will live in all the zones.

To be successful in your orchard, a fruit tree must meet several
requirements. It must be able to make its growth during the first half of
the growing season, then stop growing and harden up all new growth before
the first frost. Some people assume that a tree’s hardiness is
determined only by the cold temperature it can stand. Actually, a short
growing season may limit your choice of fruits more than the lowest
temperatures. Certain peaches, plums, and nuts are often advertised as
being hardy to –20°F. What is left unsaid is that the trees need a long
growing season to properly harden the wood so that it can stand those low
temperatures. Some tree fruits, as well as many grapes, nuts,
blackberries, and blueberries that were developed in warm zones are still
growing when the first fall frosts hit in certain areas of zones 3, 4, and
5. Since their new wood is still green and soft, the moisture-filled cells
freeze and rupture. Native plants to a region have become adjusted to
local conditions, and the shortening days trigger their growth mechanisms
to stop growing and harden their wood before frost. Imported trees (from a
milder region) are often not able to do this, and not only continue to
grow late in the fall, but also may start to grow during the first warm
week in early spring. "Provenance" refers to this difference
between adaptation to climate among members of the same species that
originated from different climate regions.

Your tree also should be able to ripen its fruit before the first
killing frosts of autumn and many late-ripening apples, such as Granny
Smith, cannot do this and therefore are completely unsuited for northern
gardens.

Finally, during the winter the entire tree — fruit buds,
branches, trunk, and roots — should be able to withstand the most likely
coldest temperatures. It should also stay completely dormant all winter,
and not begin to grow during a midwinter thaw.

--The growing season should
match what the tree needs-- it should harden properly before fall
frosts.

Southern gardeners, and those in mild winter climates such as the
Southwest and southern California, must be careful to choose the right
plants for their climate too. Plants grown in temperate zones need a
certain period of chilling during their dormant period, and can’t grow
in the tropics. The length of winter chill needed varies from a long
period for gooseberries to a far shorter one for pecans.There may be quite a range of chilling needs among cultivars,
especially for apples, with a separate list for low-chill cultivars.

In addition to the other factors that determine hardiness,
different parts of a tree may have different tolerances to cold. Often the
roots and tops of some plants are perfectly hardy but their blossom buds
are tender. Peach, plum, and pear trees all tend to bloom early, which
makes them a special target of Jack Frost, but even later-blooming fruits
like apples and grapes can be hit in areas that are prone to late spring
frosts or in unusual years.If
you have a fruit tree that always leafs out and grows, but never seems to
have fruit, this may be a cause.

Although the requirements for a specific fruit tree might seem to
limit your chances for growing it successfully, each planting zone has a
number of cultivars of a fruit that will thrive there, and you have only
to discover which do best in your area. See the chapters describing each
fruit for help in making your choices.

I sometimes hear older gardeners complain that the trees they buy
these days don’t grow as well as they used to. In the good old days, the
soil might have been better, or maybe fewer
insects and diseases were about, but a more likely reason is that trees
grew better several decades ago because they came from a nearby nursery
that grew them on the spot; or they were grafted by a local horticulturist
who specialized in joining acclimated cultivars to native wild seedlings.
By planting trees that had originated in the same neighborhood, the grower
had just about everything going for him or her.

Now, many of us have to plant trees that originated hundreds or
thousands of miles away. Northern garden centers and mass markets often
buy their stock from huge wholesale nurseries in the South or West, where
a tree can be grown to selling size in only one of their long growing
seasons. But there are a number of nurseries in each region with fruit
trees as a specialty.Often
these have a much wider selection than you can find at a garden center,
unless it is a large one specializing in plants, or a small specialty
nursery with a fruit focus.

People disagree over whether it really matters where a tree was
grown. Is a McIntosh tree grafted on a Malling rootstock in Alabama really
different from a McIntosh grafted on a Dolgo seedling in Quebec? I feel
that the ones grown closest to home always do better, and whenever
possible, these are the ones to buy. We once saw some Tennessee-grown
sugar maples planted in Vermont as an experiment. The southern-grown trees
held their leaves for a month after their Yankee companions had lost
theirs. Likewise, a few years ago some Christmas tree growers in northern
New England planted some balsam fir seedlings grown in other states. They
were surprised the following spring when the imported trees started to
grow much earlier than the native ones, and were considerably upset when a
June frost killed all the new growth.

Trees from one zone can acclimate to another zone if they are able
to survive long enough. Both the maples and the firs imported from warmer
areas are becoming more like their northern cousins each year. Trees that
are vastly unsuited for another climate, however, have little chance of
adaptation. Nectarines may never adjust to North Dakota, and the McIntosh
will probably never grow well in Louisiana.

We gardeners love to experiment and keep right on trying new kinds
that are marginal in our zone, pushing the boundaries as you probably will
too. It’s part of the joy of fruit growing.

Microclimates and Hardiness Zones

Gardeners and gardening books and catalogs are always talking about
"hardiness zones."These
are simply areas, as shown on a map, that share similar winter
temperatures.Although there
are a few different maps you may see, the main one most refer to and that
we'll use in this book is the USDA hardiness zone map.A zone on this map shares the same annual, average, minimum winter
temperature.Colors, or zones,
are in 10 degree (F) increments.So
zone 4 represents -20° to -30°F in winter.If you look closely you'll see that these zones are further divided
into half, a colder "a" and a warmer "b" region.So a garden in zone 5b would on average reach -10° to -15°F.

This map is a good starting point, but there are several issues as
already noted for winter survival to be consistent year to year.Also note this is an average.As
I like to think about it, if one of my feet is in hot water and the other
in cold, on average am I comfortable?If it is -10° one night and -30°F the next, the average may fit
the tree listing, but is the tree injured?If you really want to hedge your bets and have a tree survive you
should be looking at the extreme, not the average.Looking over the climate data in for a local city near us over 10
years, the average temperatures indicate zone 5 (-20°F) at the coldest.Yet over a couple years, the extremes got below this.All it might take is one such year to kill a marginal fruit tree.
For such trees, you may want to choose a more protected site on your
property.

Although knowing your growing zone helps a great deal when choosing
plants, every gardener soon finds out that within each zone there are many
"microclimates" where a small area may be a zone or two warmer
or colder than the surrounding area. Varying elevations, air drainage
patterns, fog, frost pockets, prevailing air currents, proximity to bodies
of water or buildings, and many other conditions cause these variances. So
while a fruit tree may be damaged by a low spot on your property where
frost settles, it may be fine up higher.

It's not as easy to protect a large row of brambles or trees from
frosts as it is to cover a row of vegetables with a frost blanket or your
favorite flowers with a sheet.Growers
may turn on irrigation to protect spring buds, for as long as water is
freezing on them they wont drop below freezing.This usually isn't economical or practical for home orchards, going
through so much water.Another
method is to keep the air circulating so frost doesn't form, as if there
were a breeze.Commercial
growers do this with large fans, which again isn't practical or economical
for most home plantings.

It frustrates gardeners who bemoan the fact that while they can’t
seem to grow a certain plant, the Joneses who live ten miles away can grow
the same cultivar with no trouble whatsoever.This is an example of "mesoclimate", between the
microclimate as on a property or neighborhood, and the climate or
hardiness zone over a whole section of the state.Mesoclimate might be a valley, area near a lake, town versus
country, or in my case the difference between living at a higher elevation
than our town 3 miles away.If
you're looking to move or buy a first home and grow fruits, keep this in
mind.

Artificial Climates

In Iceland, Alaska, and parts of northern Europe, many fruits and
vegetables are grown in glass or plastic greenhouses in order to survive
the winter. This was popular in the 1800's in England with their famous
large glasshouses and "orangeries" (for holding oranges over
winter).One of the oldest
continuously harvested grapes is in a greenhouse at Hampton Court near
London.Since North America
has a generous supply of land and an excellent transportation system,
fruit growing in greenhouses is seldom done commercially. Some home
gardeners use such houses as a hobby, however, and enjoy raising fruits
and berries that wouldn’t ordinarily grow in their zone. We have friends
who have cultivated dwarf peaches, pears, cherries, boysenberries, and
grapes near the Canadian border in small greenhouses attached to their
home.

One of these greenhouses consists only of a wooden frame, which our
friends cover with plastic in late summer and then uncover in late spring
after all danger of frost. There is a small, above-ground swimming pool in
the greenhouse to help maintain more even temperatures and provide
humidity. The ground and pool soak up the daytime heat in early spring and
fall, and release it during the cold nights, so artificial heat is seldom
needed. During the winter the ground and even the pool freeze slightly,
but since the inside temperatures are greatly modified, the widely
fluctuating outside temperatures have little effect on the trees. With the
longer growing season, the dwarf peach trees are able to complete their
growing cycle and harden their new growth. As a result our friends pick a
few dozen delicious peaches each year.

Greenhouse fruit growing is demanding. In a tight building, the
trees need extra water and, on sunny days in midwinter, the inside
temperature may rise to over 100°F. It is necessary to provide
ventilation by opening a window or installing an outside fan that works on
a thermostat. The artificial climate also can provide good conditions for
diseases and insects, since natural outdoor controls are missing, and this
may require extra spraying. Also, unless there are plenty of bees in the
neighborhood that you can let into the greenhouse at the time the trees
are blossoming, you will probably need to pollinate by hand.

All in all, however, fruit growing in a greenhouse can be an
interesting hobby. Whether or not it is worth the considerable money and
work involved is your decision. Most of us will probably choose to do our
gardening outdoors, facing the weather head-on and paying attention to the
cultivars we choose. Whether we live in Bismarck or Tallahassee, Bangor or
Spokane, nothing is guaranteed, but with planning and care there should be
enough successes to far outweigh the failures. That makes it all
worthwhile.

To sum up, I can’t overemphasize the fact that you shouldn’t
make any large plantings of fruits for yourself or as a commercial venture
until you have grown a few of them successfully in the same area for
several years. This advice comes from past experience — my own failures
and those of many other gardeners I’ve known.I've learned it's better to try lots of fruits and growing systems
and even several locations, and learn what works and what doesn't.Make mistakes and learn on a small scale.Yet I still talk to gardeners and new growers who want to start
big.Perhaps they're more of a
gambler than I am.

You can use various schemes to protect your trees from frosts, and
your trees can tolerate and regrow from mild winter damage, but the best
way to outwit the weather is to choose cultivars that are suited to your
climate and minimize their stress with proper culture. If you live in the
Deep South or a mild western climate, this means searching out plants that
have the proper chilling requirements for your climate. If you are a
northern gardener, you need ones that are hardy to the likely lowest
temperatures and that are also able to complete and harden their growth
during your growing season.